// A stack class is defined here with a private internal storage
// and public functions that can manipulate it.

// include this file in any program that needs a stack of strings
// After page 139 of C++ for Pascal Programmers by Ira Pohl
// Upgraded to 1997 style C++ in Feb 1998
// Updated to ISO C++ and modern style Wed May 12 07:13:30 PDT 2004

#include <iostream>
#include <string>
#include <cstdlib>
using namespace std;
#define MAX_LEN	255
struct stack{
private:
	string	s[MAX_LEN];
	int top_at;
	static const int EMPTY= -1;
	static const int FULL = MAX_LEN -1;
	void make_new(void) { top_at=EMPTY; }
public:

	void push(string c) { if(!full()){top_at++;  s[top_at]=c; }}
	void pop(void) { if( !empty()) s[top_at--]; }
	string top(void) { return (s[top_at]); }
	bool empty(void)	{ return (top_at==EMPTY); }
	bool full(void) { return (top_at== FULL); }

	stack(void){ make_new();}
	~stack(void){while(!empty())pop();} 

};

/***** simple tests
int main()
{
   stack s;
   s.push("a");
	cout << s.top();
   s.push("b");
	cout << s.top();
   s.push("c");
	cout << s.top();
        cout << endl;
   while(!s.empty())
   {
	cout << s.top();
	s.pop();
   }

   return 0;
}

****/